1. Field of the Invention
The present invention relates generally to a driven clutch disc forming part of a clutch used in automotive vehicles and the like, and more particularly to the clutch disc of the type wherein a hydraulic fluid is used to constitute a damper for suppressing vibration applied to the clutch disc.
2. Description of the Prior Art
Recently a clutch disc of the type wherein a hydraulic fluid is used to constitute a damper has been proposed for the purpose of effectively suppressing booming noise due to torsional resonance vibration generated in a drive system on the side of an engine power output shaft and vibration caused during acceleration and deceleration of a vehicle. This clutch disc includes the damper disposed between drive (input) and driven (output) bodies which are connected to be rotatable relative to each other. The damper consists of an elastic cylindrical member provided at the opposite ends with damper sheets which are engaged with the drive body. A relatively thin partition plate fixed to the driven body is provided to divide the inside of the elastic cylindrical member into two chambers which are filled with the hydraulic fluid. Additionally, the partition plate is formed with an orifice through which the two chambers are in fluid communication with each other for the purpose of providing flow resistance to fluid flow between the two chambers.
The thus arranged conventional clutch disc operates as follows: When a relative rotation is made between the drive and driven bodies to abruptly compress one of the two chambers, an abrupt pressure rise is produced in the compressed chamber and then gradually released through the orifice into the other chamber, thereby effectively damping torque fluctuation of a drive system. However, drawbacks have been encountered in the conventional clutch disc in which a sufficient damping effect has not been exhibited thereby making it impossible to obtain a greater damping amount, for the reason that the length of the orifice is smaller because the orifice is formed through the relatively thin partition plate.